System



1,515,370 F. M. SLOUGH MECHANICAL TELEPHONE SWITCHING SYSTEM Filed May 17, 1919 INVENTOR all ' connection with a called-tor telep Patented Nov. 11, 1924.

UNITED STATES PATENT OFFICE.

FRANK M. SLOUGH, OF ELYRIA, OHIO, ASSIGNOR TO STROliIBERG-CARLSON TELE- PHONE MANUFACTURING- COMPANY, 033 ROCHESTER. NEW YORK, A CORPORATION OF NEW YORK.

MECH.A.NICAL TELEPHONE SWITCHING- Application filled May 17, 1919.

To all whom it may concern:

Be it known that I, FRANK M. Scouorr, a citizen of the United States, residing in Elyria, county of Lorain, and State of Ohio, have invented certain new and useful Improvements in Mechanical Telephone switch ing Systems. of which the following is a iull clear concise, and exact description.

My invention relates to that class (it tele phone systems commonly known as mechanical. telephone switching systems wherein under the control of a subscribers substation controlling means, central otlicc switching; devices are directed to complete i r desired hone line of a plurality of such lines.

More specificially my invention relates to improved controlling means for such switching devices, by the use of which the switching devices may be controlled from the sub scribers telephone instrument with certainty and with a minimum oii' inexpensive apparatus.

An object of my invention is to control all of the operations of such a switch by a single relay operating under substation control, the said relay having a plurality oi? armatures operating when the relay is energized successively, there being a definite time interval. between the actuation ot the first armature and the actuation of the sec-- ond armature.

I have in the system of my invention so organized the apparatus of such a switching device, that other objects oil my invention in volving other subordinate functions oi? the devices are attained. These will he made more apparent from the description of the telephone system which embodies my invention, and a drawingoi? which accompanies this specification.

in this drawing, at A, i show a substation of a calling one ot a plurality of telephone lines a called telephone line ot which has a substation illustrated at At (T I show a central station line interconnecting: linl: circuit having incoming circuit con ductors 2, 3 and .4, and outgoing terminal switch wipers 5, 6 and 7.

l do not show the switching means and switch contacts, whereby the calling telephone line having the substation .h is connected to the link circuit C since this ini- .material so far as my present invention is Serial No. 297,949.

concerned and I may employ any of the well known means for accon'iplishing this interconnection.

At IMP, I show an impulse relay adapted to be controlled by the subscribers substation apparatus at A to operate the electromechanical switching means associated with the link circuit C as will be later described. The relay IMP contains two armatures, the one shown at 8 being a fast operating armature, and the one shown at 7 being a slow responding armature; the armature 7 is also given a relatively insensitive adjustment as compared with the armature 8. Thus the armature 8 will operate with lesser current strengths through the magnet of the relay 1MP, and will operate on current impulses of shorter duration.

The wipers 5, 6 and 97 are connector switch wipers, and are adapted when moved under the control of a primary stepping magnet PM and a subsequently operating" secondary steppinp; magnet- SM to connect with terminals. such as the terminals 9, l0 and 11 of the called line as for instance, the line having: the substation apparatus, illustrated at B. The said wipers 5, 6 and 97 are first carried step by step in a primary direction under the propelling influence of the primary magnet PM and afterwards propolled in a secondary direction under the in fiuence of the secondary stepping magnet SM, to locate first the group in which the called line terminals are located. and second to locate the said terminals in this group.

Associated with the connector switch mechanism and controlling the same, is a steering switch having); a propelling magnet SSM and having: a plurality oi? wipers and these wipers each engaging separate contact bani-rs over which they are moved, when the steering switch magnet is deenerpjized under the initial energizatioin the action oi the steering switch magnet being to always advance the wipers in the same direction upon each deenergization 01": the said magnet. The steering}; switch preferably has its bank contacts arranged in an open arc. and the wipers are preferably constructed havinga plurality of contact points disposed at different angles from the siuipportinnrotating shaft, the arrangement being such that immediately after one finger of a wiper leaves the last contact in a row of contacts, that another finger ot the said wiper will engage the first contact of the bank. Thus, the effect is produced by a single wiper finger moving from contacts arranged in a complete circle, the advantages of an open arcuatc contact bank structure however being secured. Such a switch structure is old in the art however, being illustrated in a patent to Clement, No. 1,107,153, patented August 11, 1914.

At RM, 1 show a release magnet for the connector switch, a controlling release relay being shown at BB, a common interrupter bl for a plurality of connector switches being provided to control the operation of the said release relay and the said release magnet, as will be later made apparent "from the description of the operation which "follows.

A ringing relay is shown at RG, and a ringing trip relay at ET. A switch relay SR is provided for the purpose of altering the connections from the ringing generator G, for a purpose later to be described. A source of busy tone current is shown at BZ, and may be common to a plurality of connector switches, as may also be the case with the generator G and the central exchange battery BY, illustrated in the drawing at various places, but which may be in ell'ect and usually would be, a single battery. ()fl normal contacts PON are illustrated at various points in the drawing, and control various circuits for the performance of yarious functions, as will be later understood from the description of the operation of the system which follows.

These contacts are all shown as being normally open and they will be understood as being closed immediately when the connector switch is moved from normal position. ()ther off-normal contacts are shown at SON and are normally open contacts, but are closed only when the connector switch takes its first step in a secondary direction. A double wound impedance coil 1C is shown through the windings of which talking battery for the called substation transmitter is fed, talking battery being fed through the windings of the impulse relay IMP and the impedance coil AC, to the substation transmitter at the substation A on the calling line.

The system of my invention operates, as follows: The subscriber at A, initiates the call by taking his receiver from the hook and thereby closing the hook switch contacts 12, sothat the circuit of the line conductors of the calling line are made continuous, and the line-link circuit interconnecting means is made operative to extend the circuit of the line conductors to the conductors 2 and lwhich are the talking strands of the link circuit C. A test conductor 3, normally open at the connector switch C, is for the purpose of causing the link circuit to test idle, and therefore to be seized by the calling line-link circuit interconnecting apparatus, not specifically illustrated in the drawing but understood. This connector switch mechanism is illustrated as of that type wherein the absence of potential on the test wire, such as the conductor 3, enables the link circuit to be seized by incoming calling lines, and the presence of potential, such as ground battery potential, prevents such. seizure and is placed on the said conductor after such a seizure to guard the trunk from intrusion by other calling lines. This last named action immediately takes place as will now be described.

T he telephone line conductors being extended to the talking strands 2 and l. of the link circuit, a circuit is completed for the flow of battery through the impedance coil winding AG and the winding of the impulse relay IMF, the said circuit comprising the line conductors in series and the talking set at the substation A, as well as the substation sender S and the serially included resistance coil RC, which is, however, at this time normally shunted by contacts CTS of a ringing key BK; the resistance coil and ringing key being provided for a purpose later to be made apparent.

Current from this circuit will operate the relay IMP, which relay attracting its arma tures completes a circuit for the steering switch stepping magnet $3M, this circuit being traced as follows: from the ground pole of battery, through contacts 13 of the armature 8 and contacts 15 of the armature 7. circuit conductor 1.6, lirst position contact of the steering switch wiper Vt, normal contacts 17 of the steering switch magnet, armature 18 thereof, the windin of magret SSM and the battery BY to the ground pole of battery. Current over this circuit will causes the steering switch magnet to operate its armature 18 until the contacts 17 controlled thereby are opened, whereupon the magnet will immediately retract its arn'iature, and upon such retraction a ratchet pawl carried by the armature 18 will propel the steering switch wipers l Vi, N Vi and Vi" to their second position contacts, whereupon the circuit of the steering switch magnet SSl l, just described, is broken by the wiper V7 leaving its first position con tact. Wiper W leaving its first position contact, applies ground potential to the test conductor 3 to guard the trunk circuit C,

from intrusion by other calling lines. Nip

ers 4: and 5 merely move from first to second operative position without performing any other function. l Viper moving from first to second position, conditions a circuit for the primary stepping magnet PM.

Thereupon the subscriber making the call, will operate his sending dial interrupter S, to interrupt the circuit of the line a given Jil number of times corresponding to the first digit of the called line number. it battery supply circuit which has been traced is thereby interrupted such a given number or times, the impulse relay IMP serially inchided therein will cause its armature 7 to be retracted during the period when the circuit interruptions are being made, while the armature 8 will respond to such circuit interruptions, it being retracted at each c'rcuit interruption and attracted upon each subsequent circuit closure. Upon each attraction of the armature 8, the armature 7 being continuously retracted, a circuit is completed for the primary stepping i'i'iagnet to operate this magnet, which for each operation will step the connector switch wipers 5. t and 97 one step in a primary direction. This circuit is traced as ilollows:trom the ground pole of liiattery, through contacts 12' ot' the armature S and normal contacts 14; ot' the armature 7 of the relay IMP, circuit conductor 17, steering switch wiper W and second position contact thereof, the winding of the primary magnet PM, and the battery BY, to the ground pole of the said battery. Current from this battery, will as has been said, energize the primary mag-- not PM as often as this circuit is closed, and therefore the connector switch wipers are directed to point opposite the group in which the called line contacts are located.

lVhen the series of circuit interruptions corresptuufling to the first digit of the called line have been completed, the slow responding a'i'inati'ire T of the relay Ih lP, will again be attracted and a circuit will again be completed for the steering switch magnet SSE l, In the meantime, it is to be noted that all of the normally open contacts. shown in the drawing at various places and indicated. by the letters PON, have been closed. This second circuit for the stepping magnet SSli T, may now be traced z-trom the ground pole of battery, through the contacts 13 and contacts 15 of the relay l' LP, circuit conductor 116, now closed PON wmtacts, second position contact and wiper W of the steering switch, normally closed contacts 17 of the steering swich magnet Hit, the armature 18 thereof and winding oi the said magnet, and battery BY, to the c roiu'ul pole thereof. Current lowing over this circuit, will just as in the tormer case, cause the steering switch magnet to energize, and then breaking its contacts 17 deenorgize to propel the steering switch wipers to their third operative position, this since the secondary oil-normal contacts SON are still. open, breaking the circuitof the steeriug switch magnet SSM.

The subscriber at A again operating his sending dial interrupter a second time to interrupt tne circuit of a calling line a given number of times corresponding to the cont, it; and the secondary magnet to third position contact oi the steerlng switch wiper prior to the actuation of the stepping magnet SSM, no other circuits were operative to produce any operative re sults by the functions oi"? the ditli'erent steering switch wipers into their third position. l.he secondary magnet being actuated a given number of times, will new step the connector switch wipers 5, (5 and 9? in a secoiu'lary direction a given number of steps corresponding with the number of circuit closures of the telephone line following line interruptions produced by the dial S.

the end of the second series 0t circuit interruptions the relay Hill again attracting both of its arn'iatures will operate the steering switch magnet, the circuit for the steering switch magnet this time comthird position contacts of the wiper now closed secondary oil-normal SUN, the wipers now being proinio tourth position, and the circuit is steering switch nuignet being broken the wiper i i lezving its third posi he subscriber will now depress his subst bl ringing hey Eli. to open the shunt normall; existing about the resistance coil RC, and which resistance coil is thus operativcl'y included in circuit with the line conductors to weaken the energization of the impulse relay IMP, in circuit with the said line conductors. The relay IMP will. re tract its sensitive armature 7, a circuit thereupon being closed, it the called-tor line is in an idle or unused condition, tor the ringing relay Rt}. This circuit may be traced as follows: from the ground pole of battery, through contacts 13 and contacts ot the relay 1MP, circuit conductor '17,. steering i-awitch wiper W and fourth position contact thereo't, circuit conductor 20. winding ill of the relay HG, connector switch wiper 9/7, the engaged test contact ll of the called-tor line through a winding CUR associated with the called-tor line test, contacts, of which the contact 11 is a multiple contact, and the battery BY to the ,e i'ounifl pole thereofv ei-rent from the battery BY flowing wrcr this circuit will, by traversing the winding, ill, of the relay HG, energize this relax, which will attract its arn'iatures appl ing ringing current to the called-for line rondiwliors, the ringing circuit being ill later traced. Consequently to the operation of the relay HG, the relay 19 will be operated over a circuit including contacts 22 of the relay RG, this circuit being completely traced as follows: from the ground pole of battery, normal contacts 23 of the relay SR, now closed contacts 22 of the relay RG, a second or holding circuit 2a of the relay RG, an energizing winding 25 of the relay l9, and battery BY, to the ground pole thereof.

Currenttraversing the winding will energize the relay, which energizing circuit will attract its armature, switching circuits as will be later described.

the operation of the relay RG, a circuit is completed for the flow of interrupted ringing current from the ringing generator Gr, through the interrupter i, this circuit being traced as follows: from the ground pole of battery, and then alternately through the ringing generator G and the interrupter I, to an interrupter brush 1B, a resistance lamp RL, normal contacts 26 of the relay SR, the shunted winding of the ringing trip relay RT and its shunt in multiple, now closed contacts 27 of the relay KG, connector switch wiper and co-operating called line terminal contact 9, called line conductor 28, condenser 29, bell 30, switch contact 31, called line conductor 32, called line terminal contact 10, and co-operating connector switch wiper (3, now closed contact 33 of the relay HG, resistance coil 37, the battery BY, to the ground pole thereof.

Ringing current, with superposed battery potential from the battery BY, will flow over the said called line circuit intermittently under the control of the interrupter 1, until the response of the called-for subscriber. This signaling circuit extending to the called line comprising the serially included winding of the ringing trip relay RT, which upon the response of the calledfor subscriber, will operate to disconnect the ringing current source in a manner later to he described.

In the meantime, the relay 19 having been operated, will disconnect the source of busy tone current BZ, by the opening of relay contacts 38 from the talking strand ll, lead-- ing to the calling linc, and the subscriber after pressing the ringing button to initiate the machine interrupted ringing operation, placing his receiver to his car will not hear the busy tone and will know that the calledfor line is not busy, but is idle, and that the ringing of the called line is commenced.

If the subscriber in haste or through error did not sufiicient-ly press the ringing key RK to open the contact (ITS, the busy tone current would not have been removed and the subscriber would get the busy tone and would retire his instrument instead of waiting for the response of the called-for party which would be unavailing, since the called for partys bell would not be rung in such a case.

The armature of the relay 39 of the relay 19 being operated, will close a locking circuit for the relay 19, comprising consequently closed contacts 4:0 of the armature 39 and off-normal contacts PON, this locking circuit therefore being under the control of the return to normal switch operation. At the same time greater potential is placed upon the test wiper 97, through the PQN contacts and now closed relay contacts 40 and 41 of the relay 19, to guard the called line from being seized by another connector switch which may seek to make connection with the said called line, by causing its wipers to en gage multiple terminal contacts of the contacts 9, 10 and 11, expressly illustrated in the drawing. The contacts 42 of the relay HG now being open, the consequent closure of the contacts 18 of the relay 9, will be at this time inefiective.

Upon the response of the called subscriber, a conductive bridge of the called line being accomplished by the closure of hookswitch contacts 4-3 at the station B, for the flow of direct current over the signaling circuit, which has been before-traced, direct current will flow over the said signaling circuit and through the ringing trip relay RT, causing the ringing trip relay to operate its contacts 44, which will establish a short circuit about the holding winding 24; of the ringing relay RG, deenergizing the said ringing relay which will attract its armatures' and dissociating the ringing generator from the called-for line, such dissociation being accomplish by the opening of contacts 77 and 33 of the relay RG. The locking contacts 22 for the holding circuit of the relay RG, which comprised the winding 24, are now broken.

W hen the relay R-G was deenergized, the contacts 42 were closed completing a circuit for the steering switch stepping magnet, which circuit may be traced as follows: from the ground pole of battery, through contacts 13 and 15 of the relay IMP, circuit conductor 16, now closed contacts 18 of the relay 1'5), normal contacts 42 of the relay RG, circuit conductor 4-5, fourth position contact and wipe-r W of the steering switch, normally closed contact 17 of the steering switch magnet SSM, the armature therof, the winding thereof, the battery BY, to the ground pole thereof.

Current from the said battery will flow over this circuit energizing the steering switch magnet SSM, contact 17, will again retract to propel the steering switch wipers one step to put them in fifth position, whereupon the steering switch magnet circuit will be broken, the wiper XV leaving the fourth luu ill?) position contact to which is connected the circuit conductor 45, of this energizing circuit.

The subscribers are now in convcrsationl circuit the talking strands 2 and i being extended through steering switch wipers W and W and fifth position contacts theico'l to the connector switch line wiper. 5 and (i. which are in contact with the terminals of the called line conductors. 'llhe subscribers substation transmitters receive battery current as before described. the calling subscriber through the winding of impedance coil AC, and the winding of the impulse relay 1M P, and the called subscriber through the windings of the impedance coil 1C, condensers 46 and 47 joining the calling and called talking strands. Should the (allot subscriber after first responding hang up his receiver, he may be recalled. by the ringing of his telephone bell 30, by the calling subscriber depressing the ringing key BE; in such a case the bell 30 will be rung for such periods and only during such periods as the ringing key RK may be depressed. the nunr ber of rings and the duration ott them being thus placed under the control of the calling subscriber after an initial response the called-for subscriber. This is very desiral'ile in some systems, since the intermittent ringing is annoying and is unnecessary for ring purposes.

Reringing by depressing the ringing key RK under such condition is accomplished, as follows; the subscriber depressing the ringing key RK, removes the shunt about the resistance coil RC, which being interposed in the line conductors causes the retraction of the arn'iat'ure 7 of the impulse relay IMP. A. circuit is thereby closed as follows tor the relay SR. From the ground pole of battery, through contacts 13 and 14; ot the relay IMP, steering switch wiper and fifth position contact thereof, the wind .ing of the switching relay SR, the battery BY, to ground pole thcro'l Current from this battery will operate the relay SE, attracting its armatures, the contacts 23 and 26 being opened; the contacts 23 being opened prevent a holding of the relay Eli during the rering period. The contacts 26 being open. the interrupted source of ringing current and the contacts 48 being closed completes an alternating circuit directly from the ringing generator G, through a re sistance lamp LR, the circuit from the said generator being extended from the said contacts 48 to the ringing trip relay RT, and through contacts 27 ot the relay RG, which is now operated, as will now be described, the circuit extending over the called line and through. the subscribers bell therettrom through the wiper 6, contacts 33 of the re lay RG, resistance coil 37, battery BY, to ground. A small proportion of this returnringing current will. flow in a by-path rising steering switch wiper V and titth ition contact and a winding 50 "f the i upi ance coil it), and in addition a smallv proportion. 01'? the ringing current will. traverse condenser 4.7,soine of it flowing over the calling line conductors through the calling subscribers telephone set, and back through condenser l5 and winding 51 of the inuiecance coil U}, to ground. This small amount oi? ringing current flowing in a. by path through the calling subscribers telcphone set, will audibly apprise the calling subscriber that the ringing of the called subscribeids bell is being accomplished.

The relay lit which has been before mentioned as having been operated, was operated upon the closing oi? the contacts 52 of relay tilt, these contacts closing an energizing circuit for the relay RG, this energiziug circuit comprising the battery BY, the winding oi. the relay 19, the winding 24-. of the relay lit and the contacts 52 of the relay and the relay RG will be kept operated, barring the response of the called for subscriber, as long and as often as the ringing key BK is depressed at the calling station.

The conversational circuit is re-established each time that the ringing relay RG is restored and the subscribers may converse at any such time upon the response of the called-tor subscriber. Upon the termination of the conversation, the subscriber at the station A, may automatically restore the connector switch mechanism to normal position, by placing his receiver upon the hook, opening th contacts 1:2 serially included in the line circuit, the opening oi these contacts restoring the impulse relay armature S to normal whereupon the circuit of the release relay HR is completed. whenever the segment 55 of the interrupter CI makes contact with the brush 57.

During the difiierent periods when the subscribers dial was operated vibrating the armature 8, this circuit may have been 1110- mentarily closed, but it is not sutlicient to cause the release of the connector switch by the momentary closure of this circuit, since a continued closure of this circuit comprising the contacts 58 of the relay IMP is re quired for such a period of time as may be necessarv for the contact 55 ot the interrupter CI, to travel from the brush 57 to the brush 56.

However, upon the retiring of the calling subscriber the contacts 58 are closed for a sufficient period for this to take place and the relay RE is first operated by this closure which completes an operative circuit for the relay RR, comprising the contacts 58 of the relay 1MP, PON being normal contaots,the Winding of the relay RR, normal contacts 60 thereof, interrupter brush 57 and passing contact segment 55 of the interrupter CI, resistance coil 62, and battery BY. Current from the battery will operate the relay R B, breaking the contact 60 in the abore circuit, but substituting a circuit conductor 63 leading through a resistance coil 64: to the negatiW: pole of the battery BY tor the conductor 65 interrupted by the breaking of the contact 60, The relay ER is maintained operated therefore through the contacts 58 of the relay Ill ll" for such a period as may be required to cause the segment 55 to contact with the brush 56, whereupon an energizing winding is momentarily closed for the winding 66 of" the release magnet RM, through now closed contacts 6? of the relay RE. The release magnet RM being oper ated, will operatively lock through its consequently closed contacts (38, and oil normal switch contacts PON this locliing circuit comprising a second winding 69 of the release magnet RM. At the same time circuit is completed -for the steering switch magnet SEEM, comprising switch off normal contacts PON, now closed contacts 70 of the release magnet RM, fifth position a resting steering switch wiper W normal contacts 17 of the steering switch magnet SSM, the armature and the winding of said magnet, and the battery BY to ground. The steering switch magnet will be energized attracting; its armature, thus breaking its circuit by the breaking of its contacts 17, the armature will be again retracted propelling the steering switch wipers from fifth to first. or normal position.

.Vhen the connector switch mechanism is completely restored to normal the PON contacts will all be opened, opening the various controlled circuits and all oi the apparatus involved will have been restored to normal. At the same time, the test wire 3 which has had a guarding ground potential connected to it by the switch wiper will have this potential removed when the wiper is in the first or normal position, and line-link interconnecting switching means held. operative by the presence of this ground potential will he released to sever the connection previously existing between the calling if. and the connected link circnit.

It will be understood that if the subscriber abandons the call before its completion any of thewell own circuit ZLIJK ments may be employed to restore the connector switch and its associated steering switch to normal position.

Although I have described my invention as embodied in a specific structure in which I prefer to, use it, I am aware that numerous and extensive departures may he made from the said embodiment without departing from the spirit of my invention and I do not therefore limit claims to the said embodiment but define my invention in the following claims 1. In a telephone system, a calling telephone line. :1 called telephone line sub-stat on tor each of the lines an automatic circuit interrupter at the sub-station of the calling line central otlice switching mechanism for inter-comiecting calling and called telephone lines under the control at the automatic interriu J-ters o'l calling lines; means to associate the said calling line with the said switching niechanisi'n, actuating means for the said switching mechanism adapted to actuate the same under the (,IOlltl'iJ-l ot the calling line interrupteiy. to cause it to make connection be- Ween the calling line and the desired called a signal hell the sulrslation oi" the d line automatic intermittent ringing .ch ocia'l'ed with the said switch-- 1 o 't-erat i'c under the control said calli line interrupter to inilie automatic intcru'iittcnt ringing ct said hell. means associated With the i l automatic ringing mechanism to discontinue he automatic intermittentringing); tie said bell upon the response of the 1c sire-station a ringing relay tor switching mechanism and means for actuating the same, said means be ing adapted to he subsequently operated under the control of the calling line sill s latior. pparatus to cans. the subsequent 1' oi" the called line hell at any time to the re ing 01" the called .cllfill apparatus, the said subx-icv being independent of the the ar d auliunatic intmniitten oi the said sub-stations, signal hells at each ol the said siil'i-:-1tati(ms and central ollice switching nicchauisn'i to! intcr-cruinecting calling and called telephone lines lillfltl' the control ot calling line, automatic dials. means to control the said .iing nicclumisru under the said calling line dial to cause it to inter-conned the said cell and the cal :d l let mechanism associated with ""iociatc the said *tomatic rin mechanism trom the d switching Mechanism i'i'ieans to operate the said automatic ringing mechanism when the said calling and called lines have l'ieen inte -connected by the said switching mechanism, and means to subsequently operate the said ringing relay under the cont ol of the said z-tntomatic dial after a first response oi the s ition on the called line the said ringing relay being adapted to aplll) til

(ill

ply a continuous source el ringing current to the called line 'l'or such periods as may be deteri'uined by the said calling line auto" matic dial.

3. In an automatic telephone system, calling and called. lines therefor, sub-station apparatus tor each of the lines, a connector switch to inter-connect the lines under the control of the calling line substation apparatus, a telephone signal. bell at the substation of the called line, a ringing generator associated with the said connector switch to ring the said bell, a circuit interrupter tor the said ringing generator to intermittently ring the said bell, means to lirst (.amnect the said ringing generator through the said iuterru' ner to the bell ot the called line to ring the same inter-mit tently. means responsive to the response of the called station apparatus to d'scontinue the said interrupted ringing and means re sponsive to an actuation of calling line sub-st tion apparatus subsequently to operate said signal lT-ell indc 'icndent ot the said interrupter for such a period as may be determined by the rid calling sub-station apparatus.

a. In a telephone system, lines divided into groups, an automatic switch having motion in one plane to select groups and motion in a plane at right angles thereto to select a line in a selected group, means including a relay for controlling the operation of the said switch, a single energizing winding only for said relay, means for en crg'izing the said winding comprising a source of current connected to the said winding over a line circuit, a plurality of arinatures "tor the said relay, means for rapidly interrupting the said line circuit, means whereby one (it the said armatures vibrates in response to the said interruptions and means for maintaining; the other armature in normal position during the transmission of the said impulses.

5. In a telephone system, lines divided into groups, an automatic switch having motion in one plane to select groups and motion in a plane at right an gles thereto to select a line in a selected group, means in cluding a relay for controlling the operation ot the said switch, a single energizing winding only for said relay, means tor energizing the said winding; comprising; a source of current connected to the said winding over a line circuit. a plurality oi? armatures for the said relay, means for rapidly interrupting the sa d line circuit means whereby one of the said armatures vibrates in response to the said interruptions and means for maintaining the other armature in normal position dnrine: the transmission of the said lnpulses, a ringing relay associated with. the said switch and adapted when operated to project a source ol ringing current over the selected line circuit, a resistance coil in circuit with the said relay winding at the substation oi" the line in circuit therewith, means to include the resistance coil in. circuit with the said line to control the said second arn'iature and means responsive thereto to operate the said ringing relay.

6. In an automatic telephone system. the combination with a plurality of telephone lines,v one 01'? which is a calling; line and another of which is a called line, 0t substation appexatus tor each of the said lines, a connector switch adapted to be associated with the said calling line and controlled thereby to make connection with multipled terminals of the said called line. a relay for the said connector switch, a circuit tor the said relay comprising a source of current, and the sub-station apparatus of the calling; line, a pair of independently operable arma tures for the said relay, an energizing" windfor the said relay included in the said circuit and adapted to operate the said armatures di'lierently, a CllfitlllllllltOl switch, a primary stepping magnet and a secondary stepping magnet for the said connector switch, each of the said magnets being adapted to operate under the control of one H of the said armatures to step the connector switch wipers in the direction of the said called line under the control of the said substation apparatus, circuits tor the said magnets selectable by the said distributor switch, an operating magnet for the said distributor switch operating under the control of other of the said armatures to shift the control of the first armature over the primary stepping magi'iet to the secondary stepping magnet.

7. In an automatic telephone systen'l. the comb nation with a connector switch tor making connection with a desired called telephone line, a primary magnet, a secondary magnet, and a controlling relay for the said. switch, said relay having; a pair of armatures, a calling line adapted to be associated with the said relay to control the said connector switch, a commutator for the said calling line adapted to produce successive series ol calling line interruptions, one of the said armatures being responsive to each following circuit closure after each circuit interruption, the other oil the said armatures being responsive only to the final prolonged closure after each series of interruptions. and to the act of associating the said. cell line with the said relay, a distributor switch adapted to operate under the control of the said relay at each operation of the said other armature, an automatic interrupted machine ringing mechanism adapted to cause the ringing of the hell or the called line 2 definitely spaced intervals, a manually controlled ringing mechanism adapted to cause the ringing of the said bell at and for such periods as may he desired by the calling line subscriber, said distributer switch being adapted to take successive positions at each operation, the first operative position being a primary magnet operating position, the second being a secondary magnet operating position, the third being a machine ringing operating position, and the fourth being a manual ringing operating position.

8. In an automatic telephone system a calling line and a called line. a link circuit interconnecting the l nes, means to apply a source of ringing current to the called line, an interrupter included in circuit with the said source, and means including a calling line substation apparatus adapted to subsequently substitute an alternative noninterrupted circuit between the said source and the called line.

9. In a telephone system, an incoming circuit, a plurality of outgoing circuits, a numerical switch for interconnecting said incoming circuit with any of said outgoing circuits, primary and secondary operating devices for said numerical switch, switching mechanism for determining; the sequence of operation. of said devices, a relay responsive to impulses over said incoming circuit to control the said operating devices said relay having a plurality of armatures operating out of synchronism, one of the said armatures being actuated to cooperate with said switch mechanism to control said operating devices. two of said armatures functioning to control said switching mechanism, releasing means for said numerical switch, a mechanical timing device and a controlling circuit for said releasing means completed by said timing device and said relay.

10. In a telephone system, an incoming circuit. a plurality of outgoing circuits, a numerical switch for interconnecting said incoming circuit with any of said outgoing circuits, operating means for said switch, signalling means for signalling an outgoing circuit, a switching mechanism for determinthe sequence of operation of said operating means and said signalling means, a re-- lay responsive to impulses over said incoming circuit to control said ope-rating means, said relay having a plurality of armatures operating out of synchronism, one of said armatures being actuated to cooperate with said mechanism to control said operating means. two of said armatures functioning to control said switching mechanism, releasing means for said switch, mechanical timing device and a controlling circuit for said releasing means completed by said timing de vice and by said relay.

ll. In a telephone system, an incoming circuit, a plurality of outgoing circuits, a switch for interconnecting said incoming circuit with. any 01? the said outgoing circuits, a relay controlled over said incoming circuit and provided with a plurality of armatures operating out of synchronism to control the operation oat said switch, a release relay, a mechanical timing device and a release magnet cooperating in the release of said. switch, an operating circuit for said release relay completed at said mechanical device and said impulse relay, a locking circuit completed thereafter for said release relay, and a circuit for the release magnet completed through contacts of said release relay and said mechanical timing device.

12. In a telephone system, an incoming circuit, a. plurality of outgoing circuits, a switch for interconnecting said incoming circuit with any of the said outgoing circuits, a motor magnet for advancing said switch to complete desired connections, an impulse relay having armatures operating out of synchronism and controlled over said incoming circuit to affect the operation of the motor magnet, release mechanism for said switch and a mechanical time measuring device cooperating with said impulse relay to control said release mechanism.

In witness whereof, I hereunto subscribe my name this 14th day of hlay, A. D. 1919.

F ANK M. SLOUGH. 

